Add missing support for gl_MeshViewCountNV/gl_MeshViewIndicesNV in task shaders

Update SPIRV-Tools and tests expectations

ParseHelper: don't assign xfb_offset for struct members

Add 8-bit/16-bit transform feedback support for future use

Use relative include paths in StandAlone/ResourceLimits.h

Switched to std::string for TReflection and TObjectReflection

Port Unix/ossource.cpp to Fuchsia

Fix a couple of warnings clang found

Disable Clang extra semicolon warning.

In MSVC 2017 Debug mode when a reflection is deleted (when a shader goes out of scope) xutility will fail to clear the children due to the TString allocator implementation. By switching to std::string xutility no longer throws the error.

This commit undoes the code on the commit "ParseHelper: assign
xfb_offset for struct members too" (commit
af8c1bdb), except the method renaming,
and updates the tests.

During the review of the implementation of Vulkan extension
VK_EXT_transform_feedback for the Linux Intel driver, it was pointed
that the Vulkan environment spec for SPIR-V only ever refers to block
or block members being decorated. It would be strange to not do the
same for OpenGL (ARB_gl_spirv). That would also fit better to what
GLSL does, where setting explicit xfb offsets for struct members is
not allowed.

FWIW, the original patch was proposed based on the fact that
ARB_gl_spirv is relying on OpenGL for how xfb offsets should be
assigned to members, and it was not clear (at least to me) which is
the responsible of such.

Fuchsia has pthreads but doesn't have sys/resource.h and doesn't
implement pthread_cleanup_push().

ANGLE bug: 2475

Usually this warning is disabled by default. But when turned on Clang
complains about extra semicolons in Glslang headers. Turn this off for
now. See http://crbug.com/926235

Add support for GL_EXT_YUV_target

Hopefully, this fixes the sudden new breakage with the bots.

Reflection consistency changes & bugfixes

* Previously the offset was only updated with EOpIndexDirectStruct, but we also
  need to update it for the other index types into arrays, and when expanding an
  aggregate reached after dereferencing.

Update spirv-tools known-good.

build: Do not cache debug library suffix

For nested project builds, writing CMAKE_DEBUG_POSTFIX into the cache
ends up affecting other projects. Caching this value doesn't seem to be
required in practice, so this change removes the cache tag.

Suppress a MSVC cast warning in GN.

Also came up when using the BUILD.gn file with ANGLE.

ANGLE bug: 3088

Add extension checks for NV block member builtins

Suppress inconsistent override warning in GN.

This came up when trying to roll the new glslang into Chromium.

ANGLE bug: 3088